Electronically controlled fuel injectors are known to change over time in fuel injection quantity for a given injector signal on-time. Inconsistency in the amount of fuel delivered can lead to higher undesirable emissions requirements than if the fuel injector was calibrated.
One potential solution to this problem is the periodic recalibration of the fuel injector during routine servicing. Relying on this approach, however, is dependent on the routine servicing actually occurring, and occurring at an interval-that is shorter than that which allows the fuel injector to substantially deviate from its initial fuel injection characteristics.